Notable changes to the interior include a new font type and format. The second page is a detailed table of contents and list of tables and maps. A sidebar listing all abbreviations used in the stat boxes is now located on page 3. All of the artwork has been replaced with updated pieces, including for all the new monsters described in the appendix. These occur on the upper border of the last two pages of the booklet. See pages 3, 5, 6, 11, and 28 (not particularly well spaced throughout the book, mind you) for the new artwork. Rory's diary (a Player's Handout) has been reprinted as a sidebar with an old parchment background on page 5. In addition, this handout is reproduced as a dual color part of the gate-fold cover, with the opposite side featuring a full color Player's Handout of Rory's sketch of the outer parts of the isle. All maps have been renumbered, and there is an obvious omission on Map 12 (Temple Level 1). In the first three printings, near area 5 (renumbered area 34), there was a sketch displaying the route from area 3 (now area 32) passing under a raised platform in area 5 (now area 34) to the corridor leading to the lower temple levels. This sketch has been removed in this printing, so now it appears there is no access to the rest of the dungeon. There is a letter "N." now on the map, which is a reference to the room description.
Further, several of the encounters were altered with different monsters, apparently to bring this printing in line with monster statistics available in the Basic and Expert Sets. For example, in area 2, the five bull sharks were replaced with four crocodiles. Area 6 was formerly the lair of an ancient giant squid, but in the fourth printing this has been replaced with a water termite. Area 24 once featured a sea dragon, but was replaced with a sea hydra (depicted in artwork on page 6) instead. In the lower level of the temple, giant crabs replaced the three albino mako sharks in the Chamber of the Great One, and more crocodiles replaced giant piranhas in a nearby corridor. It always vexed the author how open-water sharks could survive in a small underground chamber with freshwater fish lairing nearby. Thus, these latter two changes actually make some ecological sense, although logical dungeon ecology in the early 1980s was mildly (at best) observed.
